import { cloneDeep, uniq, get } from 'lodash'
import router from '@/router'
import setting from '@/setting.js'

// 判定是否需要缓存
const isKeepAlive = data => get(data, 'meta.cache', false)

export default {
    namespaced: true,
    state: {
    // 可以在多页 tab 模式下显示的页面
        pool: [],
        // 当前显示的多页面列表
        opened: get(setting, 'page.opened', []),
        // 已经加载多标签页数据 https://github.com/d2-projects/d2-admin/issues/201
        openedLoaded: false,
        // 当前页面
        current: '',
        // 需要缓存的页面 name
        keepAlive: []
    },
    actions: {
    /**
     * @description 确认已经加载多标签页数据 https://github.com/d2-projects/d2-admin/issues/201
     * @param {Object} context
     */
        isLoaded({ state }) {
            if (state.openedLoaded) return Promise.resolve()
            return new Promise(resolve => {
                const timer = setInterval(() => {
                    if (state.openedLoaded) resolve(clearInterval(timer))
                }, 10)
            })
        },
        /**
     * @class opened
     * @description 从持久化数据载入标签页列表
     * @param {Object} context
     */
        async openedLoad({ state, commit, dispatch }) {
            // store 赋值
            const value = await dispatch('jfAdmin/db/get', {
                dbName: 'sys',
                path: 'page.opened',
                defaultValue: setting.page.opened,
                user: true
            }, { root: true })
            // 在处理函数中进行数据优化 过滤掉现在已经失效的页签或者已经改变了信息的页签
            // 以 fullPath 字段为准
            // 如果页面过多的话可能需要优化算法
            // valid 有效列表 1, 1, 0, 1 => 有效, 有效, 失效, 有效
            const valid = []
            // 处理数据
            state.opened = value
                .map(opened => {
                    // 忽略首页
                    if (opened.fullPath === '/index') {
                        valid.push(1)
                        return opened
                    }
                    // 尝试在所有的支持多标签页的页面里找到 name 匹配的页面
                    const find = state.pool.find(item => item.name === opened.name)
                    // 记录有效或无效信息
                    valid.push(find ? 1 : 0)
                    // 返回合并后的数据 新的覆盖旧的
                    // 新的数据中一般不会携带 params 和 query, 所以旧的参数会留存
                    return Object.assign({}, opened, find)
                })
                .filter((opened, index) => valid[index] === 1)
            // 标记已经加载多标签页数据 https://github.com/d2-projects/d2-admin/issues/201
            state.openedLoaded = true
            // 根据 opened 数据生成缓存设置
            commit('keepAliveRefresh')
        },
        /**
     * 将 opened 属性赋值并持久化 在这之前请先确保已经更新了 state.opened
     * @param {Object} context
     */
        async opened2db({ state, dispatch }) {
            // 设置数据
            dispatch('jfAdmin/db/set', {
                dbName: 'sys',
                path: 'page.opened',
                value: state.opened,
                user: true
            }, { root: true })
        },
        /**
     * @class opened
     * @description 更新页面列表上的某一项
     * @param {Object} context
     * @param {Object} payload { index, params, query, fullPath } 路由信息
     */
        async openedUpdate({ state, commit, dispatch }, { index, params, query, fullPath }) {
            // 更新页面列表某一项
            const page = state.opened[index]
            page.params = params || page.params
            page.query = query || page.query
            page.fullPath = fullPath || page.fullPath
            state.opened.splice(index, 1, page)
            // 持久化
            await dispatch('opened2db')
        },
        /**
     * @class opened
     * @description 重排页面列表上的某一项
     * @param {Object} context
     * @param {Object} payload { oldIndex, newIndex } 位置信息
     */
        async openedSort({ state, commit, dispatch }, { oldIndex, newIndex }) {
            // 重排页面列表某一项
            const page = state.opened[oldIndex]
            state.opened.splice(oldIndex, 1)
            state.opened.splice(newIndex, 0, page)
            // 持久化
            await dispatch('opened2db')
        },
        /**
     * @class opened
     * @description 新增一个 tag (打开一个页面)
     * @param {Object} context
     * @param {Object} payload new tag info
     */
        async add({ state, commit, dispatch }, { tag, params, query, fullPath }) {
            // 设置新的 tag 在新打开一个以前没打开过的页面时使用
            const newTag = tag
            newTag.params = params || newTag.params
            newTag.query = query || newTag.query
            newTag.fullPath = fullPath || newTag.fullPath
            // 添加进当前显示的页面数组
            state.opened.push(newTag)
            // 如果这个页面需要缓存 将其添加到缓存设置
            if (isKeepAlive(newTag)) commit('keepAlivePush', tag.name)
            // 持久化
            await dispatch('opened2db')
        },
        /**
     * @class current
     * @description 打开一个新的页面
     * @param {Object} context
     * @param {Object} payload 从路由钩子的 to 对象上获取 { name, params, query, fullPath, meta } 路由信息
     */
        async open({ state, commit, dispatch }, { name, params, query, fullPath, meta }) {
            // 已经打开的页面
            const opened = state.opened
            // 判断此页面是否已经打开 并且记录位置
            let pageOpendIndex = 0
            const pageOpend = opened.find((page, index) => {
                const same = page.fullPath === fullPath
                pageOpendIndex = same ? index : pageOpendIndex
                return same
            })
            if (pageOpend) {
                // 页面以前打开过
                await dispatch('openedUpdate', {
                    index: pageOpendIndex,
                    params,
                    query,
                    fullPath
                })
            } else {
                // 页面以前没有打开过
                const page = state.pool.find(t => t.name === name)
                // 如果这里没有找到 page 代表这个路由虽然在框架内 但是不参与标签页显示
                if (page) {
                    await dispatch('add', {
                        tag: Object.assign({}, page),
                        params,
                        query,
                        fullPath
                    })
                }
            }
            // 如果这个页面需要缓存 将其添加到缓存设置
            if (isKeepAlive({ meta })) commit('keepAlivePush', name)
            // 设置当前的页面
            commit('currentSet', fullPath)
        },
        /**
     * @class opened
     * @description 关闭一个 tag (关闭一个页面)
     * @param {Object} context
     * @param {Object} payload { tagName: 要关闭的标签名字 }
     */
        async close({ state, commit, dispatch }, { tagName }) {
            // 预定下个新页面
            let newPage = {}
            const isCurrent = state.current === tagName
            // 如果关闭的页面就是当前显示的页面
            if (isCurrent) {
                // 去找一个新的页面
                const len = state.opened.length
                for (let i = 0; i < len; i++) {
                    if (state.opened[i].fullPath === tagName) {
                        newPage = i < len - 1 ? state.opened[i + 1] : state.opened[i - 1]
                        break
                    }
                }
            }
            // 找到这个页面在已经打开的数据里是第几个
            const index = state.opened.findIndex(page => page.fullPath === tagName)
            if (index >= 0) {
                // 如果这个页面是缓存的页面 将其在缓存设置中删除
                commit('keepAliveRemove', state.opened[index].name)
                // 更新数据 删除关闭的页面
                state.opened.splice(index, 1)
            }
            // 持久化
            await dispatch('opened2db')
            // 决定最后停留的页面
            if (isCurrent) {
                const { name = 'index', params = {}, query = {}} = newPage
                const routerObj = { name, params, query }
                await router.push(routerObj)
            }
        },
        /**
     * @class opened
     * @description 更新一个 tag title
     * @param {Object} context
     * @param {Object} payload { tagName: 要更新的标签名字, title: 新的标签名字 }
     */
        update({ state }, { tagName, title }) {
            const index = state.opened.findIndex(page => page.fullPath === tagName)
            if (index === 0) return
            if (title && state.opened[index]) {
                state.opened[index].meta.title = title
            }
        },
        /**
     * @class opened
     * @description 关闭当前标签左边的标签
     * @param {Object} context
     * @param {Object} payload { pageSelect: 当前选中的tagName }
     */
        async closeLeft({ state, commit, dispatch }, { pageSelect } = {}) {
            const pageAim = pageSelect || state.current
            let currentIndex = 0
            state.opened.forEach((page, index) => {
                if (page.fullPath === pageAim) currentIndex = index
            })
            if (currentIndex > 0) {
                // 删除打开的页面 并在缓存设置中删除
                for (let i = state.opened.length - 1; i >= 0; i--) {
                    if (state.opened[i].name === 'index' || i >= currentIndex) continue
                    commit('keepAliveRemove', state.opened[i].name)
                    state.opened.splice(i, 1)
                }
            }
            // 持久化
            await dispatch('opened2db')
            // 设置当前的页面
            state.current = pageAim
            if (router.app.$route.fullPath !== pageAim) await router.push(pageAim)
        },
        /**
     * @class opened
     * @description 关闭当前标签右边的标签
     * @param {Object} context
     * @param {Object} payload { pageSelect: 当前选中的tagName }
     */
        async closeRight({ state, commit, dispatch }, { pageSelect } = {}) {
            const pageAim = pageSelect || state.current
            let currentIndex = 0
            state.opened.forEach((page, index) => {
                if (page.fullPath === pageAim) currentIndex = index
            })
            // 删除打开的页面 并在缓存设置中删除
            for (let i = state.opened.length - 1; i >= 0; i--) {
                if (state.opened[i].name === 'index' || currentIndex >= i) continue
                commit('keepAliveRemove', state.opened[i].name)
                state.opened.splice(i, 1)
            }
            // 持久化
            await dispatch('opened2db')
            // 设置当前的页面
            state.current = pageAim
            if (router.app.$route.fullPath !== pageAim) await router.push(pageAim)
        },
        /**
     * @class opened
     * @description 关闭当前激活之外的 tag
     * @param {Object} context
     * @param {Object} payload { pageSelect: 当前选中的tagName }
     */
        async closeOther({ state, commit, dispatch }, { pageSelect } = {}) {
            const pageAim = pageSelect || state.current
            let currentIndex = 0
            state.opened.forEach((page, index) => {
                if (page.fullPath === pageAim) currentIndex = index
            })
            // 删除打开的页面数据 并更新缓存设置
            for (let i = state.opened.length - 1; i >= 0; i--) {
                if (state.opened[i].name === 'index' || currentIndex === i) continue
                commit('keepAliveRemove', state.opened[i].name)
                state.opened.splice(i, 1)
            }
            // 持久化
            await dispatch('opened2db')
            // 设置新的页面
            state.current = pageAim
            if (router.app.$route.fullPath !== pageAim) await router.push(pageAim)
        },
        /**
     * @class opened
     * @description 关闭所有 tag
     * @param {Object} context
     */
        async closeAll({ state, commit, dispatch }) {
            // 删除打开的页面 并在缓存设置中删除
            for (let i = state.opened.length - 1; i >= 0; i--) {
                if (state.opened[i].name === 'index') continue
                commit('keepAliveRemove', state.opened[i].name)
                state.opened.splice(i, 1)
            }
            // 持久化
            await dispatch('opened2db')
            // 关闭所有的标签页后需要判断一次现在是不是在首页
            if (router.app.$route.name !== 'index') {
                await router.push({ name: 'index' })
            }
        }
    },
    mutations: {
    /**
     * @class keepAlive
     * @description 从已经打开的页面记录中更新需要缓存的页面记录
     * @param {Object} state state
     */
        keepAliveRefresh(state) {
            state.keepAlive = state.opened.filter(item => isKeepAlive(item)).map(e => e.name)
        },
        /**
     * @description 删除一个页面的缓存设置
     * @param {Object} state state
     * @param {String} name name
     */
        keepAliveRemove(state, name) {
            const list = cloneDeep(state.keepAlive)
            const index = list.findIndex(item => item === name)
            if (index !== -1) {
                list.splice(index, 1)
                state.keepAlive = list
            }
        },
        /**
     * @description 增加一个页面的缓存设置
     * @param {Object} state state
     * @param {String} name name
     */
        keepAlivePush(state, name) {
            const keep = cloneDeep(state.keepAlive)
            keep.push(name)
            state.keepAlive = uniq(keep)
        },
        /**
     * @description 清空页面缓存设置
     * @param {Object} state state
     */
        keepAliveClean(state) {
            state.keepAlive = []
        },
        /**
     * @class current
     * @description 设置当前激活的页面 fullPath
     * @param {Object} state state
     * @param {String} fullPath new fullPath
     */
        currentSet(state, fullPath) {
            state.current = fullPath
        },
        /**
     * @class pool
     * @description 保存 pool (候选池)
     * @param {Object} state state
     * @param {Array} routes routes
     */
        init(state, routes) {
            const pool = []
            const push = function(routes) {
                routes.forEach(route => {
                    if (route.children && route.children.length > 0) {
                        push(route.children)
                    } else if (!route.hidden) {
                        const { meta, name, path } = route
                        pool.push({ meta, name, path })
                    }
                })
            }
            push(routes)
            state.pool = pool
        }
    }
}
